Digital images may be created by, for example, digital cameras and then processed by computers in a variety of ways. Two different digital images may be compared with each other using automated machine processes to determine similarities and differences between the images. For example, two different digital images may be compared to determine if they are substantially identical or contain an identical object. Digital images may be stored in a variety of formats and may be transcoded from one format into another format, for example in a format that supports more efficient storage and electronic communication transport of the digital image. Digital images may represent an image as an array or matrix of pixels or picture elements. Each pixel may have a value or a plurality of values that represent the subject picture element of the subject image (e.g., a small picture element of an image of a cat) as an integer value. For example, a grey scale digital image may represent each pixel element as an integer in the range of 0 to 255, where 0 is black, 255 is white, and intermediate numbers are intermediate between black and white. Alternatively, a color image may represent each pixel element by three integer values, each integer value representing the intensity of the color tone in one of a set of primary colors, such as red, green, and blue. Other value ranges are used in different circumstances.